[blykins]

It's easier to break traction in a lower gear because of the multiplication....so a slower roll in a lower gear will net an instant smoke show.

On a hard upshift, where you are barely letting off the gas, or even powershifting, you are essentially letting the engine rev up a little before the clutch engages again....thus the chirping or spinning of the tires if the clutch can hold it. If it can't hold it, then of course it will slip.